(a) All retirement allowance payments due on or after October 1, 1975, to members who retired prior to said date shall be redetermined as if the provisions of Acts 1975, No. 1103, amending Section 36-27-1, were in effect at the time the member retired; provided, that the annual retirement allowance of any member not employed as a state policeman who retired on or before January 1, 1956, shall not be less than $79.20 multiplied by the number of years of his creditable service not in excess of 30 years, in the case of service retirement, or $59.40 multiplied by the number of years of his creditable service not in excess of 30 years, in the case of disability retirement. Any increase provided in the retirement allowance payment under this section for a member who retired under the provisions of any optional benefit elected pursuant to subsection (d) of Section 36-27-16 shall accrue only to the retired member, and no person designated to receive any payments after the death of a retired member under the provisions of any such optional benefit shall receive any increase in such payments under this section.

(b) Prior to October 31, 1975, any beneficiary may elect to leave on deposit with the system all or a specified part of any increase in his monthly retirement allowance payments arising in accordance with subsection (a) of this section over the monthly allowance which he was receiving prior to October 1, 1975. The portion of each monthly payment left in the system in accordance with such election shall be credited, together with regular interest thereon, to the individual account of such beneficiary. Upon the death of such beneficiary, the total amount standing to his credit, including regular interest to the date of death, shall be paid in a lump sum to his legal representatives or to such person as he shall have nominated by written designation duly acknowledged and filed with the Board of Control.